Learn How to Choose the Best Types of Seams For Your Design Samples

Are you in the sample-making stage, but feeling overwhelmed by all the construction details? While it’s a multi-faceted process, the types of seams and finishes you use are one of the most important elements of sampling. Having knowledge of the different types of seams will not only elevate your designs, but also shape the function, aesthetic, and durability of your garment.

What is a Seam?

By definition, a seam is a line where two or more pieces of fabric are joined together. Seams help form the structure of a garment which is why they are often considered the building blocks of clothing. While many seams are purely for constructional purposes; they can also serve as decorative elements. Seams should be masterfully crafted to achieve a beautiful, well-constructed garment.  But there are many factors to consider before choosing your seam construction.

Factors to Consider When Choosing the Most Suitable Types of Seams

Type of fabric – When consulting our clients, we advise them to source fabrics at the very beginning of the design process. Many new designers don’t realize that the fabric will determine the rest of your design outcome- including which types of seams and finishes you’ll use. Are you designing a draped chiffon blouse? You’d probably want to use a french seam, for the cleanest finish. If you’re designing a line of denim; you’d probably need to use a sturdy flat-felled seam along with topstitching for added durability.

Time & Cost– Time and COST are huge factors to consider when choosing appropriate seam finishes. Different types of seams require more time and will result in added cost. For example, french seams and bias bound seams are much more tedious and expensive to construct in production than overlocked seams. When sewing leather, the seam allowances are typically opened and then glued down after sewing. If your design requires seams with a tedious finishing process like these; you’ll need to have the budget and the customer to accommodate for that price point.

Seam Location and Placement – A curved princess seam along the bust will be treated differently than a straight shoulder seam. Certain seam finishes are more suitable for curves than others, so that’s important to think about depending on where each seam lies on the body.

Garment Use/Function– It is important to think of the wearer and their lifestyle needs. For example, jeans will need sturdier seaming than a women’s silk camisole. The camisole probably won’t endure as much wear and tear as a pair of denim jeans.  Also, activewear, especially leggings, typically use flatlock seams as it allows the seam to stretch enough for the wearer to be active and get the leggings on.  The seam finishes of a good design should correspond to the needs and lifestyle of its potential wearer.

Toolery and Equipment– While many seams can be achieved on a standard industrial sewing machine, some can only be done on specific machines. Flatlock and flat-felled seams should have their own respective machines for them to be done most efficiently for production. It’s important to note that each manufacturer you meet will have different equipment and specialty machines. It’s best to discuss your designs and finishes with several factories before the production phase; this will help determine which manufacturer is most capable of producing the best result for each design. That way your options of seam finishes won’t be limited by your “go-to” manufacturer.

Most Common Types of Seams

Plain Seam:

Description- The most simple, commonly used seam. It’s both pliable and inconspicuous.

Construction- In a plain seam, at least two fabrics are joined right sides together along a line of stitching. Straight stitches are most often used to make this seam, but sometimes a tight zigzag stitch is used on knits and stretch fabrics. The seams are constructed with either a single-needle stitch or double-needle stitch; double-needle stitches add more stability and durability.

Most Suitable For- All types of fabrics except sheer, transparent fabrics as it requires a seam finish for exposed edges. Best for firm fabrics that won’t undergo frequent washing and laundering. Flowy blouses; side seams; underarm and armhole seams.

Top-Stitched Seam:

Description- Whether it’s a single or double top-stitching seam, this type of finish can be done purely for decorative purposes or to add strength and durability. Topstitching can also help reduce bulk and keep seams flat and secure on high-stress areas.

Construction- Top-stitched seams are typically straight seams that are visible from the right side of the fabric. Topstitching can be applied on top of any type of seam though it’s commonly used to stabilize the seam allowances of plain seams. This is usually done as single-topstitching or double top-stitching (which distributes bulk most evenly).

Most Suitable For- Outerwear, denim menswear, and sportswear.  Double top-stitched seams are often used for blanket edges and pocket borders.

Hairline Seam:

Description- This is essentially a plain seam, where the seam allowances are kept inside of a closed shape such as a collar or lapel.

Construction- Since these seams are often used when sewing along tight curves, they must be graded or trimmed down very close to the stitch line and pressed to achieve the best result. Hairline seams should be edge-stitched before flipping to the right side and pressing.

Most Suitable For- Collars, armhole facings, neckline facings, hem facings; all-in-one facings

Lapped Seam (aka Tucked Seam):

Description- The lapped seam is often used for joining a gathered or unfinished part to a straight or folded edge – most commonly seen in a yoke.

Construction- Much like the name, this seam consists of one fabric on top that is folded down or tucked and stitched on top of a straight edge of fabric along the seam line.  This seam should be edge-stitched close to the folded edge.

Most Suitable For- Shirt and Jacket Yokes; Heavy fabrics that are less likely to fray like suede, leather, and felt.

French Seam:

Description- French seams are often used on transparent, lightweight fabrics as they are the most delicate and the seams are most visible.

Construction- This is done by taking two fabrics and joining them wrong sides together.  Then the fabrics are turned to have right sides together, placing the seam allowance inside the seam and stitching one more time.  The French seam is both neat and sturdy as the raw edges are trimmed, and completely hidden inside the seam –also resulting in less bulk. They are usually done on straight edges; but if you clip nicely, they can be sewn on curved areas as well.

Most Suitable For- Silks; any lightweight or sheer fabrics; delicate blouses and dresses; infant-wear. Often used in eveningwear and formal sleepwear as the seams are thin and flattering yet durable, or unlined garments that need a clean, flattering finish on both the inside and outside.

Bias-Bound Seam:

Description- Bias-bound seams are perhaps the most beautiful way to finish the edges of your seams. These are often used to prevent fraying and secure raw edges of plain seams.

Construction- Bias-bound seams are formed by folding a separate bias strip of fabric over the raw edges of a plain seam and applying one or two rows of stitching to secure the tape to the edge.

Most Suitable For- Dresses, tops or other garments that are unlined; edge finishes to necklines, armholes, hems, and sleeve plackets. Best on medium and heavyweight fabrics as the bulk of the bias tape is less likely to show through, or knit fabrics where seams need to have stretch.

Flat-Felled Seam:

Description- Flat-felled seams are another great method for hiding and protecting raw edges. The seam is left neat and tidy from both sides. Flat-felled, along with counter seams, are the most reversible as they create a clean finish from both sides. These are also the strongest types of seams.

Construction- To achieve a flat felled seam, fabrics should be joined first with wrong sides together. Both seam allowances are then pressed together in the same direction. One side is trimmed down to a 1/8’’ while the other is trimmed to 3/8.’’ The raw edge of the 3/8’’ seam allowance is then folded over the shorter seam allowance with the fabric edge turned under for a clean finish.  The fold on the right side of the garment is then edge-stitched to hold it in place. The right side of the seam will show two rows of stitching and the wrong side will show one row of stitching.

Most Suitable For- Heavier weight fabrics or garments that need the utmost security. Most common in men’s sportswear; sports shirts, side seams for pants and jeans, and childrenswear.  Also used to encase boning in corsetry and eveningwear. Not ideal for tightly-curved seams.

Counter Seams:

Description: This is a highly, durable flat seam with the look of a flat-felled seam but a slightly different construction.

Construction: The seam allowances on this seam are overlapped from different directions. One piece of fabric turned down on the right side while the other adjoining fabric is turned upwards on the wrong side. From here the turned seam allowances are interlocked and edge-stitched along both folds- forming a sturdy 3-layered seam.

Most Suitable For: Thick, heavy fabrics, menswear, and reversible garments.

Welt Seam (aka Mock Flat Felled Seam):

Description- The welt seam looks like the flat-felled seam, but it’s much easier to construct.

Construction- In a welt seam, the right sides are facing together. The raw edge on the top piece is folded under for a clean finish. The fold is then edge-stitched to lock everything in place. While the right side of the seam is finished neatly, the raw edge on the wrong side is still exposed, unlike a true, flat-felled seam.

Most Suitable For- Bulky, heavier weight- fabrics that do not fray like leather, suede, and heavy-weight felt. Great for pants, and handbags.

Serged Seams and Overlock Seams:

Description- These are primarily functional seams that simultaneously join, trim, and secure the raw edges of each fabric.

Construction- These seams require either a serge or an overlock machine. These seams are joined with right sides together. The serger or overlock machines will automatically trim and enclose the raw edges with threads. The 3-needle machines are best for maintaining stretch, while 4 or 5 needle machines are best for strength.

Most Suitable For- Knit and stretch fabrics but can be used for many types of fabrics

Slot Seams:

Description- The slot seam can provide a decorative effect when a contrast fabric backed between the slot or gap of the seam.

Construction- The slot seam is very similar to the lapped seam’s construction and used for both decorative and functional purposes. A backing piece is placed between two pieces of fabric whose raw edges are turned under, almost kissing each other. The seam is then finished with topstitching along each of the lapped pieces of fabric-securing the backing piece.

Most Suitable For- Often used as a decorative stitch on coats, dresses, and skirts.

Flatlock Seams:

Description: Flatlock seams are ideal for garments with unwanted bulk that need to maintain a lot of stretch.

Construction: This join results in no seam allowance as the raw sides of the fabric lie on top of one another, encased by the multi-thread seam. They are joined by a looped chain stitch on a multi-needle machine. Flat-lock has two sides; one finished with a looped zig-zag and the other with a ladder stitch look.

Most Suitable For: Undergarments and lingerie; active-wear, etc.

Bonded, Heat-Sealed (No-Sew) Seams:

Description: Bonded, heat-sealed, or heat-welded seams create seamless garments. Bonding yields more elasticity and water-resistance, making it ideal for sportswear and athletic wear. It also results in a clear, lighter look as seams are much less prominent.

Construction: Bonding is ultimately achieved by double-sided adhesive tapes available in many different widths, colors, and textures. The adhesive tape can be implemented by a range of heat-sources such as hot-air welding, heat-press machines, lamination belts, and tacking irons.

Most Suitable For: Sportswear/Athletic Wear; Stretch garments, and design where a more subtle, less-abrasive seaming method is desired

Corded or Piped Seam:

Description- These are decorative seams that can make a big design impact on a garment.

Construction- This seam is achieved by sandwiching the edge of a fabric-covered cording between the two layers of fabric and then stitching along the seam line.

Most Suitable For- Adding decoration on edges of pillows or different types of bags, Great for contouring or accentuating parts of a garment and adding interest along necklines and hems.

Applique Seams:

Description: This seam is ideal for achieving a seamless look when joining patterned fabrics like lace or embroideries.

Construction: After matching the motifs and basting the fabrics together; this seam is achieved by topstitching the fabrics together either by hand or machine along the outline of the joining motifs. The seam disappears as the seam allowances are carefully clipped away along the patterned edge.

Most Suitable For: Haute-couture; eveningwear, lace or embroidered garments, appliques

So which types of seams will you use?  Comment below and please share with your other designer friends. If you need more assistance with the sampling and design development processes, we encourage you to check out our Source, Design, and Create Online Course! You'll learn about everything from fabric sourcing, to working with manufacturers and conducting fittings.

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